import Vue from 'vue';

// v-dialogDrag: 弹窗拖拽
Vue.directive('dialogDrag', {
    bind(el, binding, vnode, oldVnode) {
      const dialogHeaderEl = el.querySelector('.el-dialog__header')
      const dragDom = el.querySelector('.el-dialog')
      dialogHeaderEl.style.cursor = 'move'
  
      // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
      const sty = dragDom.currentStyle || window.getComputedStyle(dragDom, null)
  
      dialogHeaderEl.onmousedown = (e) => {
        // 鼠标按下，计算当前元素距离可视区的距离
        const disX = e.clientX - dialogHeaderEl.offsetLeft
        const disY = e.clientY - dialogHeaderEl.offsetTop

        const screenWidth = document.body.clientWidth // body当前宽度
        const screenHeight = document.documentElement.clientHeight // 可见区域高度(应为body高度，可某些环境下无法获取)
        
        const dragDomWidth = dragDom.offsetWidth // 对话框宽度
        const dragDomheight = dragDom.offsetHeight // 对话框高度
        
        const minDragDomLeft = dragDom.offsetLeft
        const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

        const minDragDomTop = dragDom.offsetTop
        const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight
        // 获取到的值带px 正则匹配替换
        let styL, styT
  
        // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
        if (sty.left.includes('%')) {
          styL = +document.body.clientWidth * (+sty.left.replace(/\%/g, '') / 100)
          styT = +document.body.clientHeight * (+sty.top.replace(/\%/g, '') / 100)
        } else {
          styL = +sty.left.replace(/\px/g, '')
          styT = +sty.top.replace(/\px/g, '')
        }
  
        document.onmousemove = function(e) {
            // 防止拖动的时候选中文字
            window.getSelection? window.getSelection().removeAllRanges():document.selection.empty();
            // 通过事件委托，计算移动的距离
            let left = e.clientX - disX;
            let top = e.clientY - disY;
            // 边界处理
            // if (-(left) > minDragDomLeft) {
            //     left = -(minDragDomLeft)
            // } else if (left > maxDragDomLeft) {
            //     left = maxDragDomLeft
            // }
            // if (-(top) > minDragDomTop) {
            //     top = -(minDragDomTop)
            // } else if (top > maxDragDomTop) {
            //     top = maxDragDomTop
            // }
            // 移动当前元素
            dragDom.style.left = `${left + styL}px`
            dragDom.style.top = `${top + styT}px`
            // 将此时的位置传出去
            // binding.value({x:e.pageX,y:e.pageY})
        }
  
        document.onmouseup = function(e) {
          document.onmousemove = null
          document.onmouseup = null
        }
      }
    }
  })
